endorphins

Endorphins are a class of endogenous opioid neuropeptides produced mainly in the brain and pituitary gland. The most well-known member is beta-endorphin; the term "endorphin" is often used to refer to the broader family of endogenous opioid peptides, which also includes enkephalins and dynorphins. These peptides are derived from larger precursor proteins, such as proopiomelanocortin for beta-endorphin, and are released in response to stress, pain, and various physical or psychic stimuli.

Endorphins exert their effects by binding to opioid receptors—mu, delta, and kappa—located on neurons throughout the brain and spinal cord. Activation of these receptors reduces the transmission of pain signals and produces analgesia, while also influencing mood, stress response, immune function, and autonomic processes. Beta-endorphin, in particular, is associated with feelings of well-being and natural pain relief; endorphins are also linked to phenomena such as the runner's high, laughter, sex, and acupuncture.

Endorphin signaling is part of the broader endogenous opioid system, which is the target of pharmaceutical opioids such as morphine and related drugs. Disruptions or dysregulation of endorphin pathways have been studied in relation to chronic pain, mood disorders, and addiction.